This invention relates generally to gas turbine engines, and more specifically to rotor blades used with gas turbine engines.
At least some known gas turbine engines include a rotor assembly including a row of rotor blades. The blades extend radially outward from a platform that extends between an airfoil portion of the blade and a dovetail portion of the blade, and defines a portion of the gas flow path through the engine. The dovetail couples each rotor blade to the rotor disk such that a radial clearance may be defined between each rotor blade platform and the rotor disk.
The rotor blades are circumferentially spaced such that a gap is defined between adjacent rotor blades. More specifically, a gap extends between each pair of adjacent rotor blade platforms. Because the platforms define a portion of the gas flow path through the engine, during engine operation fluid may flow through the gaps, resulting in blade air losses and decreased engine performance.
To facilitate reducing such blade air losses, at least some known rotor assemblies include a seal assembly coupled to the blade platform. More specifically, the known seal assemblies include a pair of cooperating seal members. The seal members are solid and extend radially inward from the platform into the radial clearance. The seal members are coupled to adjacent rotor blade platforms on opposite sides of a respective gap. An overall height of the seal members, measured with respect to the blade platform, is dependant upon a width of the respective gap defined between the blades. More specifically, as the width of the gap is increased, an overall height of the seal members is also increased.
During operation, as the rotor assembly rotates, circumferential loading is induced to the rotor assembly and causes the seal members to deflect towards each other. More specifically, the seal members deflect past the platform edges towards each other and across the gap to contact and to facilitate reducing fluid flow through the gap. However, depending upon a width of the gap and an elasticity of the seals, an amount of deflection between such seal assemblies may not adequately prevent fluid from flowing through the gap. The problem may be even more pronounced because the radial clearance defined between the rotor blades and the rotor disk may limit the height of the seal assembly members. Furthermore, at least some rotor assemblies include platform configurations that do not permit seal protrusion past the blade platform edges.
In one aspect of the invention, a rotor assembly for a gas turbine engine is provided. The rotor assembly includes a plurality of radially extending and circumferentially spaced rotor blades and a seal. Each of the blades includes a platform including a radially outer surface and a radially inner surface. The platform radially outer surface defines a surface for fluid flowing thereover. The seal includes at least one hollow member that is coupled to each rotor blade platform radially inner surface and is configured to reduce fluid flow through a gap defined between adjacent rotor blades.
In another aspect, a method for assembling a rotor assembly for a gas turbine engine is provided. The method includes coupling a seal assembly including at least one hollow member to at least one rotor blade that includes an airfoil, a dovetail, and a platform extending therebetween, and coupling the rotor blades to a rotor disk such that adjacent blades define a gap.
In a further aspect, a gas turbine engine is provided that includes at least one rotor assembly including a row of rotor blades and a seal. The blades are circumferentially-spaced and define a gap therebetween. Each rotor blade includes a platform including a radially inner surface and a radially outer surface. The seal includes at least one hollow member that is coupled to each rotor blade platform.